Human immunodeficiency virus (HIV) has infected over 30 million individuals worldwide. Left untreated, over 50% of these individuals will incur an oral manifestation associated with HIV. Currently, the most common oral manifestations of HIV disease are oropharyngeal candidiasis (OPC) and oral warts. In addition, HPV-associated head and neck squamous cell carcinomas (HNSCC) are increased in HIV+ individuals and have not seen a reduction in prevalence with the advent of anti-retroviral therapy (ART). The factors which determine an HIV+ individual's predisposition to OPC, HPV and other oral manifestations are poorly understood as well as how treatments for HIV influence the oral cavity and/or infections/diseases. A realistic description of the composition and diversity of the oral microflora (microbiome) is essential to understanding health and disease in the oral cavity. However, how the oral microbiome is impacted by HIV has not been described, but based on preliminary data, is expected to be significant. Moreover, ART used to treat HIV also likely impacts/alters the oral microbiome. We will use PCR-amplification of 16S rRNA genes and massive parallel sequencing to test the hypothesis that both HIV infection and ART alter the composition and diversity of bacterial species in the oral cavity and such composition can be associated with risk of oral manifestations such as HIV-associated OPC and ART-associated oral warts and HNSCC.